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L. O. HOWARD. Entomologist and Chief of Bureau. 


Entomological Assistant. 



L. O. Howard, Entomologist and Chief of Bureau. 

C. L. Marlatt. Entotnologist and Acting Chief in Absence of Chief. 

R. S. Clifton, Executive Assistant. 

W. F. Tastet. Chief Clerk. 

F. H. Chittenden, in charge of truck crop and stored product inst ct investigations. 

A. D. Hopkins, in charge of forest insect investigations. 

W. I>. Hunter, in charge of southern field crop insect investigations. 

V. M. Webster, in (lunge of cereal and forage insect investigations. 

A. L. Qitaintance, hi charge of deciduous [mil insect investigations. 

E. F. Phillips, in charge of bee culture. 

T>. M. Rogers, in charge of prev< nting spread of moths, fit Id work. 
Rolla I\ Currie, in charge of editorial work. 
Mabel Colcord. in charge of library. 

Southern Field Crop Insect Investigations. 

\Y. D. Hunter. in charge. 

W. D. Pierce, G. D. Smith, J. D. Mitchell, Harry Pinkus, B. R. Coad, R. "W. 
Moreland, engaged in cotton-boll weevil investigations. 

F. C. Bishopp, A. II. Jennings, H. P. Wood, W. V. King, engaged in tick investi- 

A. C. Morgan, G. A. Runner, S. E. Crumb, D. C. I'arman, engaged in tobacco 

insect investigations. 
T. E. Holloway. E. R. P.ariser, engaged in sugar cam- insect investigations. 
E. A. McGregor, W. A. Thomas, < ngag< d in red spider and other cotton insect 

J. L. Webb, engaged in rice inset investigations. 

11. A. Cooley, 1 >. L. Van Dine, A. F. Conbadi, C. C. Kbumbhaar, collaborators. 

Circular No. 152. 

United States Department of Agriculture, 

L. O. HOWARD, Entomologist and Chief of Bureau. 



i Lissorhoptrus simplex Say.) 

By E. S. Tuckj R, 
tomological Assistant. 


The most serious insect enemy of growing rice in the Southern 
States i- tlic rice water-weevil (Lissorhoptrus simplex Say) (fig. 1). 
When in its larval stage, the insect is known to rice growers as the 
■• rice root-maggot/' The larvae feed on the roots of rice plants, and 
the adult weevils cause some harm by feeding on rice leave-. 

Owing to the extensive growing of rice in sections of Louisiana, 
Texas, and Arkansas within recent years, the weevil has found very 
favorable condition- in the rice fields for its multiplication in propor- 
tion to the increase of the acreage and to the number of year- in 
which rice ha- been grown in any section. The development of 
definite rice-growing areas in these States ha- naturally resulted in 
particular center- of high infestation by the weevil. Rice growing 
has consequently been attended by great damage to (he crop- on 
.e count of the insect's attacks. 

Tin amount of loss that is occasioned by the attacks i-. difficult to 
estimate, a- the reduction of yield has been variously reckoned in 
different localities. Since all fields are not affected alike and differ- 
ent portions or spots of a held are apt to suffer the severest injuries, 
although the plants seldom fail outright, the growers differ much 
in their opinion.- of ill- extent of damage which they sustain, hut all 
e in the declaration that it is considerable. General statements 
of the shortage of production include a report by a grower at Beau- 
:. Tex., who placed his loss a- low as 1 per cent : hut the attacks 
in '.me fields at Stuttgart, Ark., have been severe enough to cut 
down the yield a- much as 75 per cent. 



Pig. I. -The rice water-weevil (Lissorhoptrua simplex) : a, Rice plant showing Injuries; 

h, larval scars on section of root: c, section of rootlet showing feeding scars: d, 
water line; e, c, c, roots severed by larva-; /, Injured leaf; /', enlarged section of injured 
leaf; y, adult beetle, dorsal view, much enlarged; h, antenna of beetle, more enls 
i, larva, side view, much enlarged ; /. enlarged segment of larva, lateral view ; k, 
dorsal structure of larva. (Original. I 

i ii i i RK i w \ i i i; w i t'.viL. 8 

The recent work of the bureau on the rice water-weevi] was begun 
in L910 ly Mi-. ('. E. Hood, working under the direction of Mr. D. L. 
Van Dine. The present writer began work on the problem in 1911. 
In this circular many notes made by Mr. Hood arc incorporated. 

The object of this paper is to give as much practical information 
as is h<>\\ available about the weevil and measures for its control in 
order that rice growers may make proper efforts in fighting the pest 
and secure larger crops. The cooperative facilities afforded by the 
A.gricultural Experiment Station of Louisiana, through Prof. W. R, 
Dodson, director, in providing accommodations at the State Rice 
Station. Crowley, La., and allowing free use of the unpublished notes 
comprising a preliminary investigation of the rice water-weevi] by 
Mr. Wilmon Newell, in L909, deserve grateful acknowledgment. 


The weevil was originally described in ]<'<\ as Bagous simplex 
by Thomas Say. It and another species of weevil were given the 
generic name of Lissorhoptrus by Dr. J. L. LeConte in L876. Le- 
Conte and Horn have stated thai the weevil commonly inhabits 
swampy place- throughout the eastern part of the United States. 
Its northern range extends into the Lower Peninsula of Michigan, 
according to Hubbard and Schwarz, and Dury has recorded the spe- 
cie- as being taken near Cincinnati. Ohio. It is also reported from 
New Jersey, Maryland, and the District of Columbia. Mr. E. A. 
Schwarz has concluded " that t he genus Lissorhoptrus occurs all along 
the Atlantic coast (including the Gulf of Mexico), recur- along the 
Great Lakes, and i- occasionally found inland." 

A- an injurious insect, the species first attracted the attention of 
rice farmers along the Savannah River in Georgia and South Caro- 
lina. In 1881 Dr. L. (). Howard visited a rice plantation known as 
" Proctor's," and owned by ( ol. John Screven, on the South Carolina 
side of the river, a short distance below Savannah, Ga., for the pur- 
pose of studying the insects affecting rice crops. An account of his 
observations, including notes on the rice water-weevil, was published 
in the report of the United Stale- Commissioner of Agriculture for 
1881 and 1882. But little advance has been made in further knowl- 
edge of rice-crop insects up to the present investigation. 


The adult. — The mature insect is a small, dark-gray weevil i fig. 
1, g). The technical description by Mr. E. A. Schwarz in the account 
above ment toned is here quot< d : 

Lissorhoptrus simplex.- [mago: Average length from tip of thorax, 3 mm. 
Oblong-oval, covered with large, dirt-colored scales, bul usually entirely en- 


veloped ill an argillaceous coating, which renders scales and sculpture irrecog- 
Dizable. Rostrum stout, as long as head and thorax, subeylindrical, densely 
rugosely punctulate, neither sulcate nor carinate; head densely punctulate. 
Thorax as long as wide, constricted anteriorly, lateral lobes well developed, 
sides moderately rounded, base truncate, a finely impressed median line, sur- 
face densely rugosely punctate, sides at middle with a shallow transverse im- 
pression. Elytra much wider at base than thorax and about twice as lung: 
humeri oblique, strongly declivous at apex, punctate-striate, interstices wide, 
subconvex, 3d and 5th more prominent at declivity than the rest. Presternum 
flattened, transversely impressed in front of coxae; abdomen coarsely punctate. 
Tibiae somewhat curved, armed with a strong terminal book; tarsi narrow. 
third joint not emarginate; claws slender, approximate. 

Very little difference exists between the sexes. The females usually 
have a slightly larger body than the males, and are often more dis- 
tinctly marked with a black area on the back. The marks of colora- 
tion, however, show more plainly on live moistened specimens in the 
field than on dry examples either alive or dead. According to Mr. 
W. D. Pierce, a secondary sexual character is presented by the con- 
figuration of the scrobe on the beak. He has determined that the 
scrobe of the female is slightly curved, but in the male it is practi- 
cally straight. These fine distinctions are difficult to make out with 
certainty on account of the natural curvature of the beak. 

The pupa. — No example of the pupa fit for description has yet been 
obtained, as it is very soft and any slight pressure or touch that is ex- 
erted in attempting to remove one from the mud crushes or distorts it. 

The egg. — All attempts to secure deposited eggs have afforded only 
partial results. For purposes of description dependence must at 
present be placed upon the appearance of eggs obtained by dissection 
of gravid female weevils. Mr. Wilmon Newell, in presenting a de- 
scription based upon such observations, has stated that the egg is 
pure white, cjdindrical and slightly curved in form, and has a length 
about five times the diameter. It is barely visible to the naked eye. 


Water is an element in which the weei il delights. It swims readily 
on or beneath the surface, and it feeds, rests, and mates almost as fre- 
quently in the water as above it. To determine how long the adults 
can live under water, Mr. C. E. Hood conducted a test in which one 
weevil died after passing the first 24 hours of submersion, but two 
did not die until after being kepi submerged for fully 96 hours. The 
weevil does not carry a bubble of air for breathing purposes when it 
goei below the surface, although tiny globules of air are apt to adhere 
to parts of the body. Without water, the insect can not breed. The 
eggs arc probably deposited on roots under water or in mud, and the 


larva, and doubtless also the pupa, require a bed of saturated earth in 
which to live. Wet conditions of soil with suitable vegetation a] 
to be ry for the development of all the stages. 

I OOD I'l Wlv 

The semiaquatic life of the insecl demands thai its proper food 
plants be adapted for growing in moist situations or entirely in 
water. The adult weevil itself is not disposed to feed on any plant 
unless the roots are at leasl partially covered with water or soft mud. 
In South Carolina Dr. Howard observed weevils feeding on " Sagit- 
taria. Scirpus, Cyperus, Nymphsea, and Nuphar" -plants commonly 
known as arrowhead, bulrush, galingale, water lily, and spatter-dock. 
Besides these, he reported wild rice (Zizarda aquatica) as well as 
cultivated rice (Orysa sativa). One specimen has been collected as a 
visitor on Baptisia at Victoria, Tex. All positive records of addi- 
tional food plant- refer entirely to grasses and they are the result of 
observations that were mostly made in Louisiana. Mr. Hood has re- 
ported some of the Louisiana grasses by the common name- of "bull 
grass" and "nigger's wool." which grew at Crowley. ••Hurrah 
grass" was recorded by Mr. D. L. Van Dine at Matagorda, Tex. 
Adult wee\ Lis U'^\ on the leaves of these undetermined grasses and the 
larva' were found on the root- of the first, winch was identified by 
the writer as a Paspalum ami was -aid to have been introduced into 
the count ry. " Bull grass '" is a very common term in the section and 
refers to several specii - of grasses. 

The occurrence of weevils on Walter's swale grass {Paspalum 
membranaceum) was first observed by Mr. Newell at Hake Arthur, 
La. "While similar observations have been made by the writer at 
Crowley. I. a., and Tine Bluff, Ark., the finding of larvae on the roots 
of the grass at ( 'row ley presented complete e\ idence of the true host 
relation-hip of the plant. This fact, however, may have been dis- 
covered ly Mr. Newel] two years previously at the same place where 
he found larvae infesting tie root- of a stocky Paspalum, which he was 
inclined to regard a- another species. 

Al-o during the season of 1911, at Crowley. La., the writer found 
two other species of grass which attracted the weevils from the 
nearest rice plant-. One of these was Bermuda grass (Capriola 
dactylon). It grew on a levee in a rice field which had become partly 
overflowed with the flood water. A- an attempt hail been made to 
grow it on the land previous to the rice crop, it- occurrence under 
•flooded condition- was exceptional, and no larva? were found attack- 
ing the root,. It can not lie considered a- a proper host plant. In 
the other case, a hunch of " water crab grass," undoubtedly a species 
of Syntherisina. was making a desperate struggle for existence 


within a flooded rice field. Having evidently started into growth 
before the field became irrigated, this crab grass was able to live in a 
depth of about C inches of water. Xot only were the leaves severely 
fed upon by weevils, but the roots were attacked by larvae. 


Since the growing of rice offers special inducements for the breeding 
of the weevil, clue to the attraction of the plants and the wet condi- 
tions which they demand for growth, rice has become the favorite 
food plant of the insect. Directly after the rice fields are flooded 
the weevils appear and commence feeding on the leaves of the young 
plants. In southern Louisiana, where much of the water is supplied 
by canals, the irrigation of rice fields usually begins in the first week 
of May, but the time of turning on water in different fields is often 
later, the flooding sometimes not being clone until in July to accord 
with late planting. "Where water is pumped onto the fields : a steady 
flow must be maintained for several clays before any large area of land 
can be inundated. The flooding of fields in Arkansas is not generally 
effected earlier than the middle of June. 

By following the application of water in every field the weevils 
gather most numerously on plants that stand in the depressions and 
lower portions having the deepest flood. Mr. Hood has counted as 
many as 18 weevils on a stool and 12 on a single plant. An average 
of at least 1 weevil to every 5 or G plants in one field has been 
reckoned by Mr. Newell. Some inclination to avoid direct sunlight 
during clays of hot weather is shown by the weevils, as they seem to 
prefer positions in the shade of the plants and under the surface of 
the water. 

They are rather sluggish except when swimming and are disposed 
to feign death if taken in the hand. They show no inclination to 
fly during the day and even refuse to expand the wings on being 
tossed into the air. Passage between separate plants is accomplished 
in the daytime by swimming. That they can fly for long distances, 
however, is clearly proven by their attraction to artificial lights at 
night. This propensity will be more fully discussed with reference 
to methods of control. Invasion of fields must therefore lie con- 
summated at night. 


K'ice is attacked in the same manner as other similar host plants 
and the effects of the feeding by the adults are soon manifested by 
the appearance of scars on the leaves. (Fig. 1, /.) In the act of feed- 
ing, the weevil braces its body firmly on the upper side of a leaf, and 
moving slowly forward in a longitudinal direction either up or down 
the blade, it chews out the epidermis and produces a scar, leaving 

THE RICE w \ I I i; w EEVIL. / 

the underside uneaten. These scars are very narrow, being in fact 
no wi.lri- than the spread of the mandibles, but they vary in length 
from a small fraction of an inch to more than -J inches, depending 
on the lime in which the insect engages in feeding. When the thin dries within the -car. it splits and forms an open groove 
throughout the injured space. The leaves suffer no serious ill effects 
from being fed upon unless the scars become numerous enough Lo 
cause wilting and dying. A.dults prefer tender young plants rather 
than the coarser strong growth. 

\i \ 1 1 ng \m> ovrrosn ion. 

Throughoul the period in which the weevils remain in evidence, 
mating take- plan- on nearly all occasions when a male and female 
happen to meet, and this usually occurs on a leal'. The gravid 
females crawl down the stems of the plants and evidently deposit 
their eggs singly in a puncture that i< first gnawed in a root. Mr. 
Newell ha- mentioned that he has seen adult weevils which he be- 
lieved to be females make punctures on the stems below the water 
line. Mr. Hood and the writer have watched the operations of 
lies when they apparently undertook to oviposit on rice roots 
within glass tubes. Each weevil thus observed deliberately sought 
out a place on a root anil ate into it for about a minute. Then she 
reversed her body, gripped tightly, and pressed the tip of the i 
men over the hole which she had eaten out. Mr. Hood has recorded 
that he saw the ovipositor in the form of a brown tubular organ in- 
serted into the hole. In this case the weevil remained in position 
without any apparent movement for 50 seconds before the ovipositor 
w.i- withdrawn. The writer ha- not been able to -re the ovipositor 
extended nor t.. detect an egg with certainty. The weevil may climb 
up above the water after each operation and rest for a long or shorl 
I. ..i- continue her actions among the root- for a while. One 
weevil stayed among the root- for I". minutes. 

The de\ ice that was designed and u-ed by the writer for observing 
the method of oviposition by the weevils is illustrated in figure 2. 
In it- construction a long lamp chimney was placed upright in a 
saucer and cemented at the base with plaster of Paris. A wire sup- 
port with the top bent into a loop of the proper size for steadying a 
closed-bottom glass tube, one with an inch diameter being used to 
hold the tool- of a young rice plant in water, was first placed in the 
center of the saucer. The lower end of the support was also bent in 
iral to secure firmness after being set in the plaster. By means 
of a string tied to tli, upper part of the tube, it could be lowered 
through the top of the chimney into a standing position within the 
wire loop and also removed to permit close inspection of roots and 
insects inside of it whenever desired. 

I 'ir. In2 12 2 




"Sir. Hood has stated that the larvae are first found in the rice fields 
from one to three weeks after the turning on of the water, the 

time of their inception varying 
with the weather. Hot weather 
accelerates their development. 
The young larva?, which have 
doubtless hatched from egg- laid 
in the roots, begin to feed on 
them, and in course of time as 
the larvae increase in size they 
devour or sever large portions 
of the root system. They have 
been known to eat holes in large 
rice roots and burrow into them. 
Mr. W. D. Pierce, at Beaumont, 
Tex., in 1904, found vigorous 
larva 1 consuming the entire in- 
terior of the roots. Figure 1. 
'. gives a representation of Q ix 
feeding holes made at a distance 
not more than one-fourth of an 
inch apart as Mr. Hood viewed 
them. The common methods of 
attack result in a pruning of the 
roots, after which the severed 
portions rot and the remaining 
parts are further marred with 
feeding -ear-. At this stage the 
hold of the plant upon the soil 
is greatly weakened and it can 
be pulled from the ground with 
ea-e. In some instances on rec- 
ord the root systems were en- 
tirely destroyed and the rice 
plants floated in the water. 

The injuries done by the larva; 

first cause the leaves of the rice 

plants to turn a pale yellow and 

droop, the lower blades often 

re-ting on the water. With 

severe attacks some of the leaves may die. These effects in the fields 

become most pronounced on plants growing in depressions and low 

portions of the land into which tin' water first flowed and where it 

Fn;. 2. — Lamp-chimney case for rearing 
and observing the rice water-weevil: n, 
<;ia-s lamp chimney ; '*. vessel containing 
plaster of Paris; <■. glass tube; </. wire 
support; c, rice plain : /. string lift : g, 
gauze; h, rubber band; i, ;', beetles feed- 
ing. (Original.) 

• I u \ I I l; w ! i VIL. 9 

stands deepest. As previously mentioned, such places are most 
attractive to the adults. Where the adults occur most numerously 
the larvae must be expected to follow in great number. In conse- 
quence the severity of the larval infestations is shown by a yellow 
cast of the leaves extending in broad streaks along dead furrows, 
while spots and areas of yellowish plants also become visibly ap- 
parent within the hollows and sinks of the land. These signs of 
injury have appeared in fields after 20 days of flooding, hut ordi- 
narily the larvae do not become numerous enough to cause much 
damage until the water has stood for at least a month. 

If iiian\ of the roots are cut off from a plant (fig. l. < ). it- growth 
is stunted, but as the growing rice plant possesses a strong vital power 
new nuits are put out to replace the ones destroyed, and on the cessa- 
tion of attacks the injured plant revives, or is said to "recover," 
and make- a belated growth, usually resulting in late heading. Much 
of the unequal growth of the plants in the fields, as well as the irreg- 
ular maturity of heads, is accountable to the detrimental effects of 
the larval attacks. Harvesting must necessarily be delayed until all 
the heads are ripe, thus involving the risk of loss to the normal yield 
from storms or other causes. 

Furthermore, the attack- on the roots of tender young plants pre- 
vent proper stooling or production of stems. In comparison with 
normal plant-, often less than half as many stems grow from a stool 
that has suffered damage. Shortage of heads is therefore caused by 
the failun of badly injured plants to produce a full quota of stems. 
The fact that the larvae are largely responsible for a great deficiency 
of yield in this respect will impress a comprehension of the amount 
of loss caused by the insect . 

DEVEl OPM1 NT 01 ST \'.l s. 

The length of time required for the development of the weevil 
from a freshly laid egg has been estimated by Mr. Hood to be about 
Hi weeks. Judging from the first occurrence of larvae in fields after 

1 to 3 week- of flooding, a period nol to exceed 10 day- would 

probably be ample time for an egg to hatch subsequent to deposition. 
Development is hastened with the advance of hot weather when the 
ater and soil become warm. Usually nol until about six or 

- after flooding do many of the larva? attain full growth and 
appear ready for pupation, although pupa' have been found in a field 
that at the time had been irrigated for only five week-. In prepara- 
tion for the pupal stage the larva form- a cell in the mud among the 
or at the tip of one. and Mr. Hood has asserted that the pupa 
passes two .ir three week- before it matures and the i ce of the 

adult take- pl.e i 


With the aim of working out the details of development of the 
larval and pupal stages, a number of larvae were placed on the roots 
of young rice plants, each of which was set in water within a glass 
tube, the tubes being simply stood in a holder. Attempts to carry 
through the development of pupae from larvae when subjected to con- 
stant exposure to light proved only partially successful, but better 
progress, although still lacking completeness, was made after shield- 
ing the tubes from light and supplying a small amount of earth with 
the roots and water. 


Adults as well as partially and full grown larva?, and also without 
doubt the pupae, occur in many fields up to the time of draining for 
harvest. With late crops in the coast region, however, and in the 
fields of Arkansas on account of the difference of the season in that 
State, the number of weevils in all these stages diminishes about the 
time when the plants begin to head in the latter part of August. 
Weevils found in fields after the drawing off of water to permit 
harvesting are apt to be freshly emerged individuals of a new gen- 
eration. From a collection of infested roots obtained by Mr. Pierce 
at Beaumont, Tex., June 28, 1904, adults emerged as early as July 2 
following. In case such early emerged weevils breed at once, they 
have a chance to produce a second generation in a season, provided 
they find late flooded fields or suitable water holes. At Stuttgart, 
Ark., on September 12, Mr. Hood found roots of rice infested by a 
few larvae which he regarded as representatives of a second genera- 
tion. The last larva found by the writer during his stay at Crow- 
ley, La., was taken September 25. While the weevils that emerge in 
July possihhy lay eggs for a second generation, the species is prin- 
cipally propagated in one yearly generation. 

In the spring, before many of the rice fields were flooded. Mr. Hood 
collected adults on grasses and red rice growing in ditches and other 
places containing water. Since the weevils have not been known to 
breed in such places until the soil and water become sufficiently warm, 
at which time the flooding of rice fields is well under way. the deduc- 
tion is made that low temperatures up to this time exert a restrictive 
influence upon breeding. 

Examination of roots of red rice and other plants "rowing in a 
constantly flooded ditch at Crowley. La., on October •'>. failed to dis- 
close any evidences of infestation :il the time. These results -how 
conclusively that the weevil docs not breed at this lime of year even 
in most favorable situations. Not only were the adults absent, but 
the hick of feeding scars on the leaves denoted that they had not 
visited there for some time. 



The fad thai adults live throughout the greater pari of the season 
has beer demonstrated several times. In an experiment with speci- 
mens collected at Mackay, Tex., April 5, L904, Mr. W. W. Yothers 
succeeded in keeping the weevils alive by furnishing grass for food 
until after the middle of duly. Weevils confined on rice plants by 
Mr. Hood at Crowley, La., duly IS. lived later than the middle of 
September, and the writer has made a corresponding record cover- 
ing a period from July 11 to September 21. 

The common absence if not scarcity of fresh signs of feeding by 
adult- late in the season or at the time when the new generation of 
weevils is expected to emerge throws much doubl on the question of 
their taking any food then. At least they do not remain long on the 
plants, and the few feeding -ear- that may appear to have originated 
at the time are likely produced by lingering adult- of the old gen- 
eration. A yearly overlapping of generations in the adult stage evi- 
dently occurs. Few specimens thai might be regarded as freshly 
emerged weevil- have been found in the fields. These were taken by 
Mr. I Iood. hiding in the cracks of the ground a fter the water had I ieen 
drained from the held for harvesting. Possibly some of these weevils 
stray to electric lights at night, my last capture of a weevil being 
made on the nighl of September 20. If a new generation of weevils 
occurs no evidence of it has been found. The question is. What be 
conies of them until they go into hibernation \ 

HIBERN eriON. 1 

During the fall and water of 1910 Mr. Hood made examinations 
of various places which might serve as hibernating quarters. The 
materials examined included rice stubble, loose dirt in the held-. 
straw-tacks (both old and new), grass and other vegetable matter 
along le\ee-. ;:ud Spanish moss. No weevil- were found hibernating 
except in the Spanish moss, which, however, afforded an excellent 
shelter, as the following tabulated observations made at Crowley, 
La., will show : 

Observations on the places of hibernation of the rice water-weevil. 

Oct. 26.. 
Nov. 19. 


Date m' exam] 






of w eevils 


number of 
per ton 


1 Wit i few remarks, all of the notes on hiberi the weevils 

must be credited t<> Mr. Hood, who has made the most extensive Investigate 

■ IT mile). 


As indicated by the preceding table, several thousand weevils may 
hibernate in the moss on a single tree. The appearance of large 
numbers of weevils in rice fields when they are first flooded has led 
to the opinion that the pest completes one generation on host plants 
other than rice before this time. But as already pointed out, no 
evidence has been secured that will sustain this view. Abundance of 
the weevils is probably due to their successful survival through the 
winter and emergence from hibernation. 

One reference in literature mentions the occurrence of adults " in 
wintertime under old leaves and other shelter in drier pla< es near the 
swamps." The finding of one adult in litter beneath rich stubble is 
recorded by Mr. D. L. Van Dine as the result of searching for half 
of a day at Stewart, Tex., on Octoher 28, 1909. Entrance into hiber- 
nation is probably not begun much before the time when the nights 
are cold enough for frost. Not a single weevil could be found by 
the writer in a collection of Spanish moss obtained on September 29, 
at Crowley, La., and in the preceding spring after the first weevils 
appeared Mr. Hood was unable to find any specimens remaining in 
the moss. 


Besides birds no enemy is known to feed on the mature weevils, 
although the snakes and frogs which frequent the fields probably 
do so. Bird droppings found by Mr. Hood in a rice field at Stutt- 
gart. Ark., on September 12 consisted largely of insect remains, those 
of the rice water-weevil being the most abundant. However, two 
perfect specimens of the weevil were removed from the droppings 
and one was found to be alive. According to records in the Biological 
Survey, this weevil is eaten by the long-billed marsh wren (Telma- 
todytes palustris) and the mallard duck (Anas platyrhynchos) . 

Owing to their concealment in mud the larva and pupa are secure 
from enemies. When infested roots are pulled for examination and 
larva' are washed out any minnows that happen to be present in the 
water will greedily snap the floating bodies. Predaceous larva? of 
v.atc; beetles, which also abound in flooded fields, struggle with one 
another for possession of a weevil larva. If these predators and the 
several kinds of rapacious water bugs were adapted for burrowing in 
the mud and reaching the rice roots, they would be very efficient 
oyers of both weevil larva? and pupae. But their habit of hunt- 
ing in the open -paces of water renders them of little or no service 
against the weevil. 


UK \l\l\i. 01 Till FIELDS. 

A- pointed out in the study of the life history, the existence oi the 

larva' and likewise the pupa' depends upon a saturation of the soil. 


If the soil dries out after the larvae have made an advance in growth, 
they soon die. Tin- practice of draining fields and allowing them 
to dry enough to cause the death of the larvae was first proposed in 
1881 by Col. John Screven, a rice planter in South Carolina, and was 
indorsed by Dr. Howard after his investigation in the field in l v M. 
of the rice growers in Louisiana and Texas have reported good 
ts from periods of draining, while others have claimed that the 
plants suffered more from being deprived of water than from at- 
tacks. Many growers therefore advocate deep flooding of fields as 
proper treatment of rice when infested by the weevil larvae. 

Different results of draining are mainly accountable to the ex 
of damage done by the larva' at the time of releasing the water. 
When the roots have been hut slightly or not yet severely attacked, 
draining seems to result very effectively in most cases by the reduc- 
tion of the number of larvae to a minimum. Effectiveness depends 
on the length of time that plants can stand -without water and not 
suffer from the want of it. Plants that have a fair hold of roots 
show no ill effects of drying spells lasting from 5 to 10 days without 
rain. In case of heavy rain, drying should he carried on for some 
longer or until the. surface of the ground forms a dry crust and 
begins to crack. This f drying has been found very effective in 

causing the death of larva-, and the ground has still retained sufficient 
■ -ire below the surface to sustain the plants that possessed a large 
proportion of root-. 

On the other hand, when roots have become severely pnmed. the 
plants are unable to endure draining without being further impaired. 
Instead, they need a plentiful supply of water in order that new roots 
can he put out and growth resumed. The value of draining is de- 
pendent upon the enforcement of the practice at the proper time, 
which the grower can easily determine by making examinatioi 
the roots. Many growers object to draining on account of the • 
of water and the risk or difficulty of getting fields promptly flooded 
again. If fields were so arranged that water could be turned from 
one to another in succession or from early to late plantings, most of 
the i >uld he utilized and the saving in the cost of pumping, 

where this mean- of supply is employed, would he an item of coi 
eration. Other benefits arising from change ter will be men- 

tioned later. Continuance of flooding to enabl< nine 

inpirv by larva-, instead of taking steps to destroy the . will. 

a- Mr. Newell has inferred, probably lead t<> a regular in 
the number of weevils until the point i- reached where, the ii 
will make profitable rice culture impossible. Coi 

loes not in the least inconvenience the Ian ondi- 

even more favorable for them. Being the most practical method 
of controlling the weevils, draining of field- .3 highly im- 




Conclusive observations upon tests of draining conducted by the 
writer or under his instructions during the season of 1911 are pre- 
sented in the following statements. 

At Crowley. La., en June 9, a rice grower drained some parts of 
his field of early planted Honduras rice in which fully one-fifth of the 
plants, then at a height of 15 to Is inches^ showed yellow blades. 
The roots had been rather severely pruned, but enough remained 
together with newly grown ones to permit draining with safetv. 
As many as six and seven larva? infested the roots of a stool. Reflood- 
ing was effected June 19, after a period of drying which had lasted 
nearly 10 days. Quite a noticeable difference existed between the 
drained and undrained rice on July 21. The plants in the drained 
areas had nearly all headed out uniformly, while most of the un- 
drained rice was behind in growth, either not having headed or hav- 
ing heads just formed and blooming. Regarding recovery, the ownei 
said that the plants which grew in the fresh water after reflooding 
soon lost their yellow color and took on a vigorous growth of healthy 
green, but in the undrained parts with standing water the plants re- 
covered much more slowly. At harvest time the owner estimated 
his best yield on land that had been drained to check the weevil 

In the field of another grower, however, results were not so suc- 
cessful. These small young plants were not injured badly and 
showed only incipient spots and streaks of weak yellow color. This 
was a variety of Japan rice. The field was drained May 29 and re- 
flooded June 8, giving a drying of 10 days. One week after reflood- 
ing the plants had taken on a fresh green color, and the infestation of 
the most injured roots had been reduced to a minimum, as shown 
by the nearly normal growth. Owing evidently to a second infesta- 
tion, during which no draining was done, an irregular belated growth 
was displayed at heading time. Whether the outcome might have 
been worse without any draining can only be surmised. 

Acting under a cooperative agreement. Mr. C. G. Haskell reported 
some very important results of his examinations at Almyra. Ark. 
On draining a. field July 20 In- found 25 larva' on the roots of 25 
sfools. On flooding the field July 28 he found only two larvae on the 
same number of roots. The result was accomplished by eight days ^<( 
draining and drying. A stool usually produced live stalks or stems. 
By calculating percentage- of infestation according to the number of 
stalks the draining must have reduced the proportion of larva' from 
20 pel- cent to L.6 per cent. 

Again, on draining a field July 25 Mr. Haskell found 50 larvae on 
the roots of 25 stools, hut on reflooding the field July 31 he found no 
more than 9 larva' per 25 stools. The draining and drying therefore 


lasted six days, and calculating on ;i brsis of five stalks to a stool the 
tation was reduced from 10 to 7.2 ] >•■ r cent. The writer's own 
examination of this rice on August I. the second day of refiooding, 
gave substantial evidence of the reduction of larvae in corresponding 
numbers, the count resulting in 3 larvae on the roots of 10 stalks. 

Ai Pine Bluff, Ark., on August 5 the writer made examinations 
in a rice field that had been drained for five days. On the roots of 
I", stalks only nine larvae were found alive. The infestation there- 
fore amounted to approximately 9 per cent. The owner stated that 
before draining two and three larva? occurred on a -tool. Calculating 
five stalks per stool, the infestation then could nol have been less than 
33 per cent. In sonic places the ground was still saturated, but most 
of it was stiff mud. Thai the draining really caused a reduction in 
the number of larvae by death was evidenced by the finding of two 
dead ones, and some of the live ones seemed weak as if about ready to 
die. Not many roots were badly cut and the draining began at an opi 
portune time. The pumping of water on this Held was resumed 
August 8, but ii was not wholly Hooded until a few days later. The 
drying covered seven days at least. No rain fell during this time, 
and the ground had begun to crack from drying. The results were 
considered very beneficial, as the larvae caused no further trouble and 
the rice headed out splendidly. 


Direct observations, as well as the testimony of growers, I 
brought out the fact that rice growing in running water suffers little 
from weevil attack-. In these cases, however, no considerable area 
ha- yet he. mi -ecu in which the water flowed with any perceptible cur- 
rent. To maintain a distinct moving Hood over a large field would 
require an immense supply of water. The instance- that have been 
observed were confined i" -pot- or -mall plat- covered by the inflow 
of water from ;i canal or ditch. In spreading onto a Held from an 
inlet the current soon loses fop-,, and any low temperature. Where 
;i cool How of water i- pumped from a well directly onto a Held the 
low temperature seems to exert n controlling factor against infesta- 
ticn. But these cases arc rare, because the rice demands warm tem- 
peratures for vigorous growth, and the -un heat greatly restricts the 
1 area. 


Deep water ami stagnant water greatly favor development 
weevil-. A- already pointed out, rice in -pot- or areas of deep 
ing i- most severely attacked. Severity of attacks i- especially 


marked in shallow water almost as much as in deep water when 
either heroines stagnant. In a field that had received only a scant 
supply of water, which in fact merely filled the low places although 
keeping all of the ground soaked, very few larva' could be found. 
Most of these larva? occurred on roots of weak plants in the pools, 
while the best growth stood out of water and was scarcely attacked 
at all. Soaking instead of flooding appeared to result very bene- 
ficially, not only controlling infestation but inducing prime growth of 
plants at least past the stage "of stooling when the coarse leaves offer 
little attraction to the weevils. 


Rice in different fields that were first flooded at various times 
covering a seasonal range of dates in accordance with the planting 
and sprouting has in due course been found subjected to the same 
degree of infestation. No advantage can he gained against the weevil 
by choosing any particular time for flooding that will still be suit- 
able for the needs of the plants. An attempt to delay full flooding 
by a gradual soaking of fields in order that the plants might attain 
a strong growth and be able to withstand or escape attacks after 
deep water was applied met with interference from heavy rainfalls 
which flooded the fields, and the owner then saved the water. The 
probable effectiveness of soaking is indicated by the case of accidental 
shortage of water, as mentioned in the preceding subject. 


At Crowley, La., on June 28, inspection was made of a field of rice 
that had been allowed to dry out from stoppage of water supply on 
two occasions, one lasting six days and the other four days. The oc- 
currence of larvae was limited principally to the most heavily flooded 
parts, and the roots of the plants were not badly injured. The com- 
parative scarcity of the larvae throughout the field was attributed to 
the effects of the two intervals of drying, and the rice escaped much 
danger from attacks. 

At Almyra. Ark., on August 1. other observations were made on a 
field where scarcity of water had caused alternate periods of drying. 
Water had been supplied but little more than half of the time since 
first Hooding, though the ground had been generally kept damp with 
the addition of rainfall. No larvae were found on the roots of this 
rice, and Only a few weevils occurred on weak plants near 1 he edges 
of the field. The plants exhibited a high, vigorous, and fairly 
healthy growth, the laclc of enough water having evidently resulted 
in a yellow tinge of the leaves, which, however, promised to be 

BK i w \ I i i: w EEVTL. 


speedily overcome owing to flooding rains. The crop eventually 
produced an excellent yield. 


In an experiment to determine whether the use of fertilizers and 
application of lime would serve as a check on weevil infestation, plats 
for growing rice were prepared at Crowley. La., as shown by the 
accompanying diagram, which also gives the results of examinations 
on July 8. The whole field was flooded equally to an average depth 
of G inches. The arrangement and treatment of the plat- and status 
of infestation are outline. I as follow-: 



Limed. 2.000 

iiounils [.or 



;> larva 


1 larva. 

11 la: 

Acid pi inds, 10 per 

7 larva 


C larva . 

Acid phosphate m< above i>lus muriate 
oi potash, 60 pounds per acre 

11 larvi 


9 larva-. 

7 lar 

Total proportionate number of larvae: 

For the cheek plat 17. or 22jj per cent infestation. 

For the phosphate plat 19, or l'.v. per ceul infestation. 

For the phosphate and potash plal 30, or 10 per cent infestation. 

Calculating another way from the foregoing outline, the limed 
areas were found to have ■_'! larvae compared with 1G larva' in the 
unlimed areas of the same plat, while in the opposite plat 26 larvae 
were taken on the roots of < be same number of sta Iks. 

No advantage in reducing or retarding infestation appeared to be 
shown through the application of fertilizer- or lime to the soil, bul 
rather the contrary effects are indicated, as the strip with double 
fertilization contained the mosl larvae. Since the plant growth had 
responded in proportion to the d< : fertilization, the stimulated 

plants exhibited uo signs of injury resulting in yellow appearance of 
Leaves except in the limed areas, which a> a whole included the 
poorest growth on account of the severer pruning of the small root 

Further observations made at Midland. La., have led to the con- 
clusion that fertilization doc- uot prevent nor even hinder the pro- 
pagation of larvae, but the extra nourishment may assist the plants 
to overcome attacks. 



The appearance of adults at artificial lights at night has suggested 
the plan of placing lights in the fields and trapping the weevils which 
may be attracted. Great numbers of the weevils seek the electric lights 
of stores in the towns throughout regions where the insects abound. 
( )rdinary lights in dwellings are sometimes frequented. At Crowley. 
La., more than a hundred weevils have been collected within a few 
minutes on a single store window. They appear most numerously 
on warm dark nights, but, like many other insects, they do not fly to 
lights in any considerable number when the moon shines. Neither 
does the time of their flight seem to last long, for as soon as dark- 
ness has settled, most of them come in a rush, and only occasionally 
do stragglers show themselves later in the night. Their seasonal 
appearance begins from the 1st to the middle of April, and about the 
middle of August they become very scarce. 

Tests of the efficiency of light as a practical means of attraction 
were conducted at Crowley. A portable acetylene outfit was used to 
furnish light, being operated near rice fields 1 mile from town. Some 
of the best results were as follows, the weevils being taken on a 
cloth screen that was provided for the purpose of inducing them to 
alight : 

On the night of May 26, 1910, Mr. Van Dine started the light at 
8 o'clock and captured over 40 weevils in the first 15 minutes. Later 
the breeze increased and only strong flying insects came to the light. 

Starting the light at 8 o'clock on July 19, after a day of heavy 
rains. Mr. Hood collected - 1 weevils in 45 minutes. But on the night 
of July 29, which was clear and warm with slight south breeze, be 
placed the light in the middle of a rice field and caught 12.") weevils 
between 8 and 9 o'clock. 



When the weevils gather in particular portions of a rice field, as 
they often do along deeply flooded edges, dead furrows, and in spots, 
opportunities seem to be presented whereby the application of a food 
poison could be made. effective. As the weevils indulge in rather ex- 
tensive feeding compared with their size, the poisoning of the 
plants would be apt to cause the death of great numbers of the adults 
that might feed upon the poisoned leaves. The application of the 
poison should be made upon the first appearance of the insects before 
they have had much chance to oviposit. The poison must be selected 
with reference to its safety on the plants, and if in the form of a 
powder, it could be easily distributed by means of a dust gun. from 

I in BK i w \ i t t; w EE\ l!,. 19 

which it mighl be spread for some distance by wind. Probably the 
only danger would be to live stock having access to the water the 
drinking of which would be a remote possibility. 

i I I 1 I i: \1 MANAGEMENT. 

Clean cultural management in dealing with the weevil as with 
other crop pests is advisable. By restricting the growth of the 
various grasses and other plant-, particularly the objectionable red 
variety of rice, which grow along and within canals, ditches, and 
water boles, much advantage could be derived toward the suppression 
of the breeding of the weevils on the uncultivated host plants. Drain- 
age of bayous, sinks, and water hole- would doubtless be of great 
benefit for the control of the weevil alone. 

Leveling of the surface of fields that are to be planted in rice and 
plow ing in such a manner as to avoid dead furrows as much as | 
hie would obviate many of the depressions which on being deeply 
flooded conduce to a high infestation of the plants in such place-. 

Finally, a thorough preparation of the -oil before planting is to he 
recommended, in order that grass and weed- ma\ he eradicated with- 
out the necessity of deep flooding for the purpose of drowning them. 
Thi.- will permit very -hallow flooding with periods of draining or 
mere soaking of fields for the control of infestation and the better- 
ment of the crops. 

-I M M \KY. 

The rice water-weevil causes more damage to rice crops in the 
Southern State- than any other insect affecting rice plant-. When it 
is in the larva] stage it commit- severe injuries to rice plant- by de 
stroying the root-. Some harm i- done by the adult- in feeding on 
the leaves. 

The insect chooses food plants that grow in wet places and it 
breeds only where it finds water. Eggs are evidentlj laid on root- in 
water or mud. under which condition- tin' larvae hatch, feed, grow, 
and transform into pupae, and finally the adult- mature and emerge. 

Two generations may possibly be produced in a season, hut one 
generation seems to he the rule. Adults pas- the winter in hiberna- 
tion, appearing in spring and invading the rice held-. 

The most practical means of controlling the weevil consists in the 
practice of draining and allowing infested rice fields to dry suffi- 
ciently at tic propel- time or before the attacks of larvae have greatly 
weakened the plants. Alternate flooding and drying, if carried out 
properly, will accomplish the same results. Very -hallow flooding 
or soaking of fields re-train- infestation. Fertilization assists the 
plants to overcome injury. 



Considerable numbers of weevils can be captured at lights and 
destroyed, and the possibility of poisoning them in fields needs to be 
put to the test. Cultural management should be directed with the 
view of enforcing every advantage against the weevil that will be 
consistent with the welfare of the crop. 


James Wilson, 

Secretary of Agrit uZture, 
Washington, D. C, April 12, 1912. 

ADDITIONAL COPIES of this publication 
-Ti- may be procured from the Superintend- 
ent of Documents, Government Printing 
Office, Washington, D. C, at 5 cents per copy 


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